Traps at the Al2O3/CdSe interface

Abstract

The effect of traps at the Al₂O₃/CdSe interface on thin‐film transistors (TFT’s) is experimentally measured and mathematically modelled. These traps are shown to lead to a decay of the ON current with time which has a t^−αkT behavior for the first msec, decreases to log t for about 20 sec, and then saturates. The OFF current increases with log² t for as much as 200 h before saturating. Capacitance and conductance measurements are reported which characterize the fast and slow states. The temperature dependence of the drift in the TFT characteristics is presented. A model for the origin of the fast and slow states at and near the Al₂O₃/CdSe interface is developed. It is then shown how the presence of the fast traps improves TFT characteristics for application in a liquid crystal flat panel display.